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1.
DONG-NING ZHANG 《地震学报(英文版)》1999,12(2):148-154
The numerical dynamic model of Chinese mainland lithosphere's stress and strain field was constructed with elasto-viscous creep constitutive relation. The most recent data of the stress field of Chinese mainland and the horizontal movement velocity of the crust blocks were used as constraint conditions. The values of the boundary force were computed by trial-and-error method. The effect of the Qinghai-Xizang Plateau's excess potential energy to the movement of Chinese mainland was studied also in this model. The results of the numerical computing show that, recent rapid raising of the Qinghai-Xizang Plateau and the generation of normal faults in the southern part of the plateau resulted from the convergence of Indian Plate to the Eurasian Plate, and also from the rapid convective thinning of the lower lithosphere. Horizontal extension of the Qinghai-Xizang Plateau is the main dynamic factor to form the present tectonic framework of the Chinese mainland. The compressive loads on the eastern boundary of the model were mainly applied by the subduction of the Pacific Plate. The compression from the Philippine Plate maybe slight. 相似文献
2.
Current crustal movement in Chinese mainland 总被引：2，自引：0，他引：2
王琪 《地震学报(英文版)》2003,16(5):574-582
The quantification of tectonic deformation in the Eastern and Central Asia is of great significance for the study on global plate motion and lithospheric dynamics. In the past four years, the velocity field of horizontal crustal movement for the Chinese mainland has been established for the first time thanks to the intensified GPS measure-ments and its improved accuracy. The velocity field derived from GPS measurements delineates the patterns of tectonic deformation in the Chinese mainland in the unprecedented detail, and thus reveals the new features of the ongoing tectonic process resulted from the collision of Indian plate to Eurasian plate. Meanwhile, the surface offset induced by two strong earthquakes occurred in Chinese mainland was sampled precisely using InSAR technique. 相似文献
3.
Based on the available and supplementary survey data,it analyzes the effect of seismicity in Taiwan and the Taiwan Straits on the southeastern coastal area of the Chinese mainland and discusses its roles in seismic hazard prevention and textual research of historical earthquakes. The results show that the frequency of strong earthquake in Taiwan area is high,with a time interval ranging from several to dozens of years,but the maximum influence intensity of seismicity from there to the coastal areas of the Chinese mainland is only VI degree; while the maximum influence intensity of the seismicity along the littoral fault zone located on the west of the straits reaches VIII ～ IX degree because of the shorter distance to the Chinese mainland,though the frequency of strong earthquakes is lower than that of the Taiwan area. Strategies for protecting against seismic hazards in the southeastern coastal area of China are proposed. Besides focusing on the effect of strong earthquakes of the littoral fault zone,attention also has to be paid to the low-cycle fatigue failure of engineering structures induced by the earthquakes in Taiwan and the stir effect on society induced by earthquake phobia. It is concluded that it would be more accurate and proper to take the May 19,1517 earthquake recorded in the Chinese mainland area as the influence of a strong earthquake in the Taiwan area. 相似文献
4.
Current crustal motion and deformation in the Chinese mainland and its surrounding area determined from GPS data 总被引：1，自引：0，他引：1
Based on the geodetic data taken from the National GPS Network established by China Climbing Program "Investigation of Crust Motion and Geodynamics in Modern Time",we derived the movement velocities of the GPS sites. In terms of the power series expansion of a rotation function for horizontal velocities on a spherical surface proposed by Haines and Holt (1993), we computed the horizontal velocity and strain-rate field. We preliminarily studied the appearances and characteristics of the present-day crustal movement and deformation in the Chinese mainland with the computed results. The researches demonstrated: ① The present-day crustal movement and deformation in the Chinese mainland are being jointly controlled by Indian, Pacific and Philippines Ocean Plates and Siberia-Mongolia block, and these three large plates and block form a situation of tripartite confrontation, but Indian Plate seems to play a leading role; ② The North-South Earthquake Zone plays an important adjustment role in the present-day crustal movement and deformation process, displaying clear characteristics of demarcation line of tectonics in large areas; ③ There seems to be another adjustment zone along the latitude line approximate N35°, but its characteristics are less obvious than that of the former; ④ Dynamic actions of these three large plates and block on the Chinese mainland are dynamic stable; appearing in stable push-press velocities. These results are generally accorded with the results determined from geology, geophysics, and seismology. By the contrast with seismicities, it appears preliminarily that there is some corresponding relation between intense shear strain zone and future strong seismicity area, but this problem needs further examination of earthquake examples. 相似文献
5.
Gkarlaouni Ch Papadimitriou E E Karakostas V G 闻学泽 金学申 Kilias A 潘华 杨家亮 《地震学报(英文版)》2008,21(2):181-201
Coulomb stress changes associated with the strong earthquakes that occurred since 1904 in Sichuan and Yunnan provinces of China are investigated. The study area comprises the most active seismic fault zones in the Chinese mainland and suffers from both strong and frequent events. The tectonic regime of this rhombic-shaped area is affected by the eastern extrusion of the Tibetan highland due to the collision of Eurasian Plate against the Indian lithospheric block along the Himalayan convergent zone. This movement is accommodated on major strike-slip intraplate fault zones that strike in an E-W direction. The gradual 90° clockwise rotation of the faults in the study area contributes to the complexity of the stress field. The seismic hazard assessment in this region is attempted by calculating the change of the Coulomb Failure Function (?CFF) arising from both the coseismic slip of strong events (MS≥6.5) and the stress built-up by continuous tectonic loading on major regional faults. At every step of the stress evolutionary model an examination of possible triggering of each next strong event is made and the model finally puts in evidence the fault segments that apt to fail in an impending strong event, thus providing fu-ture seismic hazard evaluation. 相似文献
6.
Earthquakes are a serious natural disaster faced by countries all over the world. Research on earthquake hazard mitigation are important parts of earthquake science and is a feature of China''s development of earthquake science. In recent years, the Ministry of Science and Technology (MOST) of the People''s Republic of China, the National Natural Science Foundation of China (NSFC) and the China Earthquake Administration (CEA) have attached great importance to basic research on earthquake hazard mitigation, and new opportunities and challenges have emerged. This paper collects the applications and approvals of the National Key R&D Program and the NSFC projects undertaken by the research institutes of the CEA system in recent years. The CEA system has received funding in the 13th “Five-year Plan” for “Monitoring, Early Warning and Prevention of Major Natural Disaster”. The implementation of these projects is expected to provide support for the basic science and applied research of the CEA system. In the NSFC, the number of applications from the CEA system is relatively stable, and the funding rate is slightly higher than the average for the department of earth science. Although no detailed statistical analysis has been performed, the CEA system still has room for improvement in the application of talent and major programs. I hope that the brief review of new opportunities that have arose in recent years described in this article can provide some background and new thinking for future challenges. 相似文献
7.
In the process of solving Euler vectors based on GNSS horizontal movement field, the number of estimated parameters can affect Euler vector results. This issue is analyzed through theoretical deduction and practical example in this paper. Firstly, the difference between the results of Euler vectors in different solving models is deduced. Meanwhile, based on GNSS horizontal movement field in the Chinese mainland from 2004 to 2007, two common models （ RRM and REHSM） are used to discuss the impact of solving models on Euler vectors and the follow-up study. The result shows that the maximum value of the difference in a block＇s entire rotation can reach 2. 6mm/a, and should not be ignored. Therefore, the results of horizontal movement are different using different kinematic block models, and this should be paid more attention in the analysis of crustal horizontal movement. 相似文献
8.
Based on GPS data from 1991- 2004 and the least-squares collocation method,we analyze the crustal deformation in the Chinese mainland. The results show that the first-order crustal deformation is unchanged in different periods in the Chinese mainland,which reflects the background of regional tectonic activity. The strain rate is much higher in Western China,especially in the Qinghai-Tibetan Plateau and Sichuan-Yunnan area. The variations in different periods are related with seismicity of strong earthquakes during the same time. The GPS data after 2004 shows the post-seismic deformation of the 2001 Kunlun Mountains M S8. 1 earthquake. 相似文献
9.
Introduction Jiashi-Artux area in southwest Xinjiang is one of the most active earthquake provinces at pre-sent in Chinese mainland. In the last century, about 3/4 strong earthquakes in Chinese mainland hit this area, and especially from January 21 to April 16 in 1997, 7 earthquakes with the magnituderanging from 6.0 to 6.9 occurred in a very small area of 9 km×18 km near Jiashi (ZHU et al, 1998). It has never taken place before in Chinese mainland that a series of strong earthquakes shoo… 相似文献
10.
Surface waveform modeling has played an important role on many continental-scale studies of upper mantle ve-locity structure, but it was seldom applied to the Chinese mainland study. The present study firstly analyzed sur-face waveform fittings for eight wave paths crossing through four different regions of the Chinese mainland (east-ern, central, northern and western China), and then inverted for 1D path-averaged S-velocities for these paths. The inverted crustal and upper-mantle S-velocities showed obvious region-related features, which are well consistent with known geotectonic units and previous research results. These results indicate that surface waveform modeling is a reliable method to get crustal and upper-mantle velocity structure. Furthermore, this method has a prominent advantage in detecting upper-mantle structure compared with fundamental-mode surface-wave dispersion method. 相似文献
11.
Ice crystal clouds have an influence on the radiative budget of the earth; however, the exact size and nature of this influence has yet to be determined. A laboratory cloud chamber experiment has been set up to provide data on the optical scattering behaviour of ice crystals at a visible wavelength in order to gain information which can be used in climate models concerning the radiative characteristics of cirrus clouds. A PMS grey-scale probe is used to monitor simultaneously the cloud microphysical properties in order to correlate these closely with the observed radiative properties. Preliminary results show that ice crystals scatter considerably more at 90° than do water droplets, and that the halo effects are visible in a laboratorygenerated cloud when the ice crystal concentration is sufficiently small to prevent masking from multiple scattering. 相似文献
12.
本文分析讨论了实验地震学研究中很少论及的岩石破裂和破坏的很大差异,指出仅以岩石破坏实验模拟地震特别是前兆研究存在诸多不足.建议以岩石破裂来模拟地震特别是前兆研究,由此可给出较为完整的地震活动图像.岩石破坏前兆已研究的相当多,但大破裂前则未必出现如破坏那样的前兆.大破裂前兆特征比破坏前兆更能反映地震前兆的复杂性,其识别更难,更符合实际.同时议及以岩样的整体黏滑模拟地震研究特别是前兆研究的不足.建议加强对局部现象——大破裂（或黏滑）的前兆特征、预测方法的深入仔细研究. 相似文献
13.
Richard M. Worthington 《Annales Geophysicae》1999,17(2):257-272
A simple method is described, based on standard VHF wind-profiler data, where imbalances of echo power between four off-vertical radar beams, caused by mountain waves, can be used to calculate the orientation of the wave pattern. It is shown that the mountain wave azimuth (direction of the horizontal component of the wavevector), is given by the vector
are radar echo powers, measured in dB, in beams pointed away from vertical by the same angle towards north, south, east and west respectively, and W is the vertical wind velocity. The method is applied to Aberystwyth MST radar data, and the calculated wave vector usually, but not always, points into the low-level wind direction. The mean vertical wind at Aberystwyth, which may also be affected by tilted aspect-sensitive layers, is investigated briefly using the entire radar output 1990–1997. The mean vertical-wind profile is inconsistent with existing theories, but a new mountain-wave interpretation is proposed. 相似文献
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16.
J. M. C. Plane 《Annales Geophysicae》2000,18(7):807-814
It is proposed that a component of meteoric smoke, sodium bicarbonate (NaHCO3), provides particularly effective condensation nuclei for noctilucent clouds. This assertion is based on three conditions being met. The first is that NaHCO3 is present at sufficient concentration (104 cm–3) in the upper mesosphere between 80 and 90 km. It is demonstrated that there is strong evidence for this based on recent laboratory measurements coupled with atmospheric modelling. The second condition is that the thermodynamics of NaHCO3(H2O)n cluster formation allow spontaneous nucleation to occur under mesospheric conditions at temperatures below 140 K. The Gibbs free energy changes for forming clusters with n = 1 and 2 were computed from quantum calculations using hybrid density functional/Hartree-Fock (B3LYP) theory and a large basis set with added polarization and diffuse functions. The results were then extrapolated to higher n using an established dependence of the free energy on cluster size and the free energy for the sublimation of H2O to bulk ice. A 1-dimensional model of sodium chemistry was then employed to show that spontaneous nucleation to form ice particles (n > 100) should occur between 84 and 89 km in the high-latitude summer mesosphere. The third condition is that other metallic components of meteoric smoke are less effective condensation nuclei, so that the total number of potential nuclei is small relative to the amount of available H2O. Quantum calculations indicate that this is probably the case for major constituents such as Fe(OH)2, FeO3 and MgCO3. 相似文献
17.
本文应用特征分析综合信息矿产资源评价的原理,利用现有地质、物化探、遥感资料对香花岭地区的矿化程度进行深入分析,以汇水盆地为统计单元并通过应用数量化理论Ⅲ分别从26个统计单元中筛选出21个单元作为模型单元,从47个变量中筛选出41个变量,建立多矿种和单矿种特征分析定量模型4个,对该区不同的单元矿化程度进行定量评价和预测研究.定量地给出预测该区的Ⅰ级成矿远景区（中型矿区）,Ⅱ级成矿远景区（小型矿区）,Ⅲ级成矿远景区（矿点）的关联度和找矿标准. 相似文献
18.
The Global Ozone Monitoring Experiment (GOME) onboard the ERS-2 satellite has been in operation since July 1995. The Norwegian ground-based total ozone network has played an important role both in the main validation during the commissioning phase and in the validation of upgraded versions of the analysis algorithms of the instrument. The ground-based network consists of various spectrometer types (Dobson, Brewer, UV filter instruments). The validation of the second algorithm version used until January 1998 reveals a very good agreement between GOME and ground-based data at solar zenith angles <60° and deviations of GOME total ozone data from ground-based data of up to ±60 DU (∼20%) at zenith angles ≥60°. The deviations strongly depend on the season of the year, being negative in summer and positive in winter/spring, The deviations furthermore show a considerable scattering (up to ±25 DU in monthly average values of 5° SZA intervals), even in close spatial and temporal coincidence with ground-based measurements, especially in the high Arctic. The deviations are also dependent on the viewing geometry/ground pixel size with an additional negative offset for the large pixels used in the backswath mode and at solar zenith angles ≥85°, compared to forward-swath pixels. 相似文献
19.
Many Large Eddy Simulation (LES) models use the classic Kessler parameterisation either as it is or in a modified form to model the process of cloud water autoconversion into precipitation. The Kessler scheme, being linear, is particularly useful and is computationally straightforward to implement. However, a major limitation with this scheme lies in its inability to predict different autoconversion rates for maritime and continental clouds. In contrast, the Berry formulation overcomes this difficulty, although it is cubic. Due to their different forms, it is difficult to match the two solutions to each other. In this paper we single out the processes of cloud conversion and accretion operating in a deep model cloud and neglect the advection terms for simplicity. This facilitates exact analytical integration and we are able to derive new expressions for the time of onset of precipitation using both the Kessler and Berry formulations. We then discuss the conditions when the two schemes are equivalent. Finally, we also critically examine the process of droplet evaporation within the framework of the classic Kessler scheme. We improve the existing parameterisation with an accurate estimation of the diffusional mass transport of water vapour. We then demonstrate the overall robustness of our calculations by comparing our results with the experimental observations of Beard and Pruppacher, and find excellent agreement. 相似文献
20.
Numerical solution of the scalar and elastic wave equations has greatly aided geophysicists in modeling seismic wave fields
in the complicated geologic structures containing hydrocarbons and hence increases the geologic interpretation. Finite-difference
method offers a versatile approach to compute synthetic seismograms numerically for given subsurface complex geological structures.
To avoid the spatial derivative of the elastic parameters and density, elastodynamic equation (first-order hyperbolic equation)
has been solved using the Lax-Wendroff scheme. A numerical finite-difference modeling program has been developed for the P-SV
wave using the above solution. A line source with a time delay of 0.015s and dominant frequency of 120 Hz has been utilized
in the simulation. In order to avoid the large values of the displacement vector in the source region,Alterman andKaral's method (1968) has been utilized. Horizontal and vertical component synthetic seismograms have been computed for two different
geological models with and without oil and gas bearing zones. It has been concluded from the response that a finite-difference
technique not only yields the relative arrival times but also accounts for the variation in amplitude and phase according
to the elastic impedance contrast across the interfaces. It should come as no surprise to learn that in spite of the limitation
of this numerical method, the scheme has provided a valid response for the thin layer, high acoustic impedance contrast and
the pinch out. 相似文献